Surgeons use a variety of suture anchors to conduct soft tissue repair procedures. For these procedures, one or more sutures called “repair” sutures are attached to a suture anchor, which is or will be fixed to bone. The repair sutures are used to tie soft tissue down to the bone. There are many challenges to joining a repair suture to a suture anchor.
One kind of suture anchor used in soft tissue repair procedures is secured into/within bone through an interference fit with a pre-drilled bone hole. Maximum interference fit is desirable because it results in higher bone fixation strength and less chance of the anchor pulling out of bone. The issue arises, however, when attempting to obtain the maximum interference fit with small diameter anchors (e.g., on the order of 1 mm-3 mm).
As anchors decrease in diameter without height change, their column strength also decreases. Lower column strength makes it more difficult to insert small diameter anchors into bone, especially when the bone is dense. In short, because small diameter anchors are less structurally sound and require greater force to insert them, there is an increased risk of small diameter anchors failing when inserting them.
Another kind of suture anchor used in soft tissue repair is an expanding suture anchor. Expanding the suture anchor inside a bone hole creates a radial force of expansion. This force presses against of the walls of the bone hole and secures the anchor to the bone. One of the problems with the expanding anchor is that once expanded, there is no way of knowing that the expansion of the anchor has been retained with surrounding pressure from the bone hole pressing back in on the radial force of expansion.